Introduction

• NFL summary data –> 2009 - 2018

Focus: “Competitiveness” across the NFL

• Distributions of team success over time
• Differences across divisions (AFC vs NFC)
• Similarities in play styles (pass/run and offense/defense)
• Historical consistency of teams – how likely are upsets?

Data

• NFL season summaries from 2009 - 2018

Identifying info:

• team name
• season
• division

Outcome variables:

• wins/losses/ties
• points scored
• points allowed

Data

Offense / Defense Stats

• offensive points made

• expected points

• defensive points made

• expected defensive points

• broken up two ways:

  • passing vs running plays

  • per attempt vs total across season

Manipulation: Creating New Variables

• more general divisions (removing north/south/east/west)
• win / loss ratio (wins / losses per season)
• win record (double positive, positive, negative, double negative)
• total offensive yards gained
• total defensive yards allowed

Question 1: Divisions

• 2 Major Divisions:
  • National Football Conference (NFC)
  • American Football Conference (AFC)
• Is either division becoming more competitive over time (fewer outlier teams)?
• Does either division appear to have clear dominant teams, or do a variety of teams take the spotlight in different years?

Is either division becoming more competitive over time?

Are there clear dominant teams, or are victories spread out across teams?

Takeaways - Divisions

Competitiveness over time

Competitiveness across divisions

Question 2: Pass/Run

Can teams remain competitive with different passing/running strategies?

Does either passing or running dominate among the most competitive teams, or are play styles similar across all teams?

Observations: Pass vs Run

Question 3: Offense/Defense

Are offense and defense equally important for a team to be competitive?

What separates the good teams from the bad teams?

Observations: Offense/Defense

• There are very few teams that only have a good offense OR defense

• Teams that perform well appear to be good at both
  • High scoring
  • Don’t allow many points

• What separates a bad team from the worst teams?
  • The worst teams have very poor offenses
  • A good defense does not guarantee that a team is competitive

• What separates a good team from a bad team?
  • Worse defensive performance
  • Offense is important, but you can’t neglect your defense!

• What separates a good team from a great team?
  • Sometimes defensive improvement, sometimes offensive
  • Big Idea: You can remain competitive with different styles of play!

Question 4: Consistency

• Are the top teams consistently good?

• How much variation is there between teams across the years?

• Is the NFL competitive in terms of upset possibilities?

Graphing consistency

Zooming in:

• A few teams that are consistently bad
• Most decent to good teams have significant performance variation
• Notable outliers: Carolina, Green Bay, Indianapolis
• Outliers + variation = chance for upsets
• Divisions seem somewhat balanced in terms of skill

Conclusions

• The NFL is very consistent, and has remained so over time
• There are only a few teams that perform extraordinarily well
  • These are not the same every time
• The best teams are not unbeatable
  • Outliers show a chance for upsets
• The best teams pass more than average, but teams that run more can also succeed
• Different balances of offense and defense can lead to success. Not only one strategy!

Limitations

• Passing vs Running and Offense vs Defense stats would be more informative if per-game, rather than per-season
  • Allow much more direct comparisons between yards and points
  • Averaging across the season is less accurate

• Only have data since 2009. Older data might look different.

• In addition to win/loss, would have liked overall rank in season

Future Questions

• Can we determine the strength of the relationship between offense/defense and win probabilities?
  • Does one have a stronger mathematical relationship to chances of winning?